1. Technical Field
The present invention relates to a printing apparatus provided with a transporting unit that transports a medium such as a sheet and a printing unit that prints onto the medium and a printing method.
2. Related Art
In the related art, a printing apparatus that has a transporting unit that transports a medium, including a sheet, and a printing head that prints onto the medium is well known (for example, JP-A-2000-198189, JP-A-2012-45860, and the like).
For example, in order to cause a liquid discharged from a printing head to land at an appropriate position on a medium, a technique of correcting discharge timing according to a gap between the printing head and the medium and a relative moving velocity between the printing head and the medium is disclosed in JP-A-2000-198189.
A printing apparatus that detects a medium jam with photo interrupters provided on an upstream side and a downstream side of a carriage is disclosed in JP-A-2012-45860.
In addition, an image reading apparatus that controls a transporting unit by detecting an oblique movement and a paper jam of a document based on image data obtained by a medium being imaged by a linear image sensor is disclosed in JP-A-7-336491. In this image reading apparatus, it is determined that there is a jam of the document (paper jam) in a case where the fact that oblique movement amounts of the document at different positions are significantly different from each other is detected using a plurality of image sensors provided at different positions on a transporting path of the document.
Meanwhile, since the gap between the medium and the printing head changes once the medium being transported is lifted, a landing position at which ink droplets discharged from the printing head land on the medium deviates from a target position, thereby leading to a decline in print quality. In addition, the lifting of the medium causes a jam or causes the medium to scratch the printing head. In JP-A-7-336491, although the jam of the document can be detected, once time for stopping the driving of the transporting unit is delayed until the oblique movement amounts become significantly different at the different positions at a time of jam occurrence, the jam is intensified and a work of eliminating the jammed medium, including the document becomes complicated for a user. For this reason, it is desirable to detect the lifting of the medium at a time of jam occurrence or the lifting of the medium that causes jam occurrence and to stop the driving of the transporting unit. In addition, once the medium scratches the printing head, the printing head is brought to a state where an appropriate printing cannot be carried out. Accordingly, an extra operation of cleaning the printing head is required to bring the printing head back to a state where an appropriate printing can be carried out. Since such displacement of the medium in the direction (for example, lifted direction) that intersects the surface to be printed of the medium cannot be detected, this type of defect of the printing apparatus attributable to the displacement of the medium in the lifted direction occurs. This type of problem is not related to the type of printing apparatus such as a serial printer, a line printer, and a page printer, and is also not related to a printing system such as an ink jet type and a dot impact type. This problem is common in the printing apparatus.